Fix MSVC linker error

Apparently, MSVC does not like whenever a fully templated class is
exported.

Change-Id: Ie920720d645941925b4ee04d9ae2b92e6c061f2b

include/ceres/manifold.h

diff --git a/include/ceres/manifold.h b/include/ceres/manifold.h
index 24eac23..4d6e9fa 100644
--- a/include/ceres/manifold.h
+++ b/include/ceres/manifold.h
@@ -238,7 +238,7 @@
 //
 //    EuclideanManifold<ceres::DYNAMIC> manifold(ambient_dim);
 template <int Size>
-class CERES_EXPORT EuclideanManifold final : public Manifold {
+class EuclideanManifold final : public Manifold {
  public:
   static_assert(Size == ceres::DYNAMIC || Size >= 0,
                 "The size of the manifold needs to be non-negative.");